Are you telling me guys like Jones/Cain/JDS/Aldo/Benson aren't evolved beyond Penn/Liddell/Randy/Fedor? They are on a higher level than any of them, and it's been what 5 years roughly since all those guys were on top?
MMA is still in a position where fighters who were at the top of the heap (and have been around a long time) are being defeated and outclassed by newcomers. When Jones won the championship, Machida/Shogun/Rampage/Rashad were some of the highest ranked fighters ever, and it was considered the deepest division in MMA. Jones, a 23 year old at the time gets a title shot and destroys all of them. He's the youngest champion in UFC history.
New guys like Gustafsson and Glover are beating guys like Shogun/Rampage. They have evolved beyond them. It was what, 3 years ago when Shogun was going to reign the LHW divison forever, and a year before that when Machida was?
What does Velasquez do so much different than Emelianenko¿ They both have/had high pressure striking and good take downs (one via wrestling the other via Sambo/Judo) and good GnP. Both have good cardio. Yet Velasquez would have to show some significant submission skills to be considered an as complete fighter as Emelianenko. What is Velasquez so much more than maybe a finetuned version Emelianenko. (And with only three successful title fights he still has quite a way to show the same dominance over his devision as Emelianenko did)
Benson Henderson is like a smaller copy of St. Pierre, good allround fighter with his wrestling based style, good striking and good grappling (and lack of finishing ability). Yet the younger fighter is significantly less dominant than St. Pierre.
Dos Santos shows similarities to a boxing centric version of CroCop in Pride. Striking centred fighting with good TDD and good timing.
It's pretty easy to see how MMA is still evolving at a quick rate. It's not as big of a jump as UFC1 to whatever, but it's still a big leap every few years and a very noticeable one.
If it's so easy to see how MMA is/has been massively evolving in recent times, you should be able to name it in what way the big leaps of evolution have come.
As jhizzy has said, the newer fighters beating the older fighters doesn't necessarily mean they have evolved beyond the older fighters at their respective prime. Particularly not "massively". Beating Mauricio "constant knee problems" Rua these days is not a measure stick for greatness. And Glover won a decision against Quinton Jackson who lost a decision to Bader. As I said, it's rather finetuning what's happeining at this time.
The only one of the "new breed" who may show exceptional allround fighting skills is Jones with his physical gifted body and his pronounced wish to follow the footsteps of Anderson Silva. He has yet to significantly improve his punching power though, particularly if he really plans to move up to heavy weight where he doesn't have the strength advantage over his opponents to greco ragdoll them like at LHW.